A Michigan referee who was seriously injured when a player assaulted him during a match Sunday died Tuesday morning, two of his friends and a medical examiner told the Los Angeles Times.

John Bieniewicz, a 44-year-old father of two, was trying to eject a player from an adult soccer match Sunday in Livonia when the man punched him in the jaw, said James Acho, a longtime friend of the referee.

Mary Mazur, a spokeswoman for the Wayne County Medical Examiner's Office, told The Times that Bieniewicz was pronounced dead at 9:38 a.m. Tuesday at Detroit Receiving Hospital. An autopsy will be performed Wednesday, she said.

Bassel Abdul-Amir Saad, 36, was charged with assault with intent to do great bodily harm, according to the Wayne County Prosecutor's Office. He appeared in court Monday and remains in custody in lieu of $500,000 bond.

Assistant Prosecuting Attorney Maria Miller told The Times that charges had not been upgraded as of early this afternoon.

Calls to the hospital and the Livonia Police Department were not immediately returned. Saad's attorney, Brian Berry, did not immediately respond to requests for comment.

Bieniewicz was knocked unconscious by the blow and suffered a serious injury, the Livonia Police Department said in a statement. Police said there were several witnesses to the attack.

Acho said Bieniewicz grew up in suburban Detroit, and the two were part of a larger group of friends that remained close after meeting at Detroit Central Catholic High School in 1984.

Bieniewicz was a "standout" football and basketball player in high school, and he developed an interest in soccer after working for the men's team at the University of Michigan in Dearborn.

He became a licensed referee at every level, Acho said, and he had been working as an official on weekends for more than 20 years.

"On a Saturday or Sunday, he might referee a college game, then he might drive and referee a high school game, and then at night he might do an adult rec league game," Acho said. "He was all over the map."

In two decades, Acho said his friend had never had a physical altercation with a player on the pitch.

"He was a very mild-mannered guy, very non-confrontational and very professional," Acho said.

Bieniewicz worked as a supervisor of pediatric dialysis at Mott's Children's Hospital in Dearborn, Acho said. He had been married for 16 years, and had two children, who are 13 and 9, friends said.

A group of 10 high school friends always kept in touch via email, and Bieniewicz always updated the group on international soccer news.

“He would email all of his friends about the World Cup because none of us knew anything about soccer," Acho said.

Bieniewicz had recently become president of the Metro Detroit Soccer Officials Organization, according to Acho.

Jeff Szajnecki, a Pittsburgh resident who played basketball and football alongside Bieniewicz in high school, said Abdul-Amir Saad's team was new to the league. He didn't think Bieniewicz knew the man who is accused of throwing the punch.

“It’s just so sad that he basically got killed doing something that he loved," Szajnecki said.